Of all the U.S. players embroiled in the FBI’s investigation into Russia’s election meddling, just one is under surveillance. On Tuesday, The Washington Post revealed that federal officials are monitoring the communications of Carter Page, a 45-year-old businessman who has worked in the Russian energy sector and is a vocal supporter of the Kremlin.

If the name Carter Page leaves you asking “who?” then you’re not alone. Page, a former foreign policy adviser to the Trump campaign, was never more than a bit player. Last March, Trump name-dropped him as one of his advisers and then, as Page’s support for Russia was revealed in the following months, dropped him altogether.

Reporters who went foraging for information on him during the race for the White House found little. Within Trump’s team, no one seemed to know who hired him, or what he did for the campaign. Among U.S. businessmen who had worked in Russia, and the Russians they had worked with, few knew Page’s name. In a scathing Politico article about Page, an unnamed Western investor in Russian energy told the author: “I can poll any number of people involved in energy in Russia about Carter Page and they’ll say, ‘Carter who? You mean Jimmy Carter?’”

Carter Page: A Brief History

Carter Page was born in Minnesota on June 3, 1971. Raised in Poughkeepsie, New York, he went on to enlist in the U.S. Naval Academy, where he was a Trident scholar. He left the academy in 1993 as a distinguished graduate and spent five years with the Navy before securing a fellowship at the Council of Foreign Relations, an independent, nonpartisan think tank based in New York City .

Finance followed policy and after completing his MBA at the Stern Business School, Page began working as an investment banker for Merrill Lynch in 2000. After stints in London and New York, he opened the firm’s Moscow branch in 2004 and served as the chief operating officer of Merrill’s Energy and Power Group.

Page has boasted that while in Russia, he was involved in some of the 2000s biggest energy deals, including the privatization of RAO UES, an electric power holding company that once controlled 70 percent of Russia’s electricity transmission lines.

According to Politico, however, people involved with these deals either didn’t remember him—suggesting that Page might have inflated his resume—or had nothing much to say about him. “He wasn’t great and he wasn’t terrible,” Page’s former boss, Sergei Aleksashenko, told Politico . “What can you say about a person who in no way [is] exceptional?”

From Russian Banker to Trump Adviser

In 2008, after Page returned from his allegedly unmemorable time in Russia, he set up his own investment management company called Global Energy Capital. The two-man operation—Page’s partner is a man called Sergei Yatsenko who was formerly employed by the Russian state-owned gas company Gazprom—has failed to strike any significant deals.

Page also began writing for the Global Policy Journal, an academic publication based at the U.K.’s Durham University. In February 2015, he wrote a bizarre article titled : “New Slaves, Global Edition: Russia, Iran and the Segregation of the World Economy.” In it, he argued that the U.S.’ National Security Strategy, which included aggressive sanctions on Russia over its actions in Ukraine, parallelled an 1850 publication on how to produce the ideal slave.

A year or so later, Trump’s campaign were scouting around for policy advisers and Page’s name made the list. One staffer told Politico the campaign’s co-chair, Sam Clovis, was the one who recruited Page. (Clovis has refused to confirm this).

It is not clear why anyone would have picked Page as an adviser. He was not a leading businessman in Russia nor someone with particularly good contacts. By all accounts, he can’t even speak Russian.

But, in early 2016, Trump’s campaign was desperate. On March 2 of that year, 122 members of the Republican national security community had signed an open letter saying Trump was unfit to be president.

Deserted by many experts, Page might have seemed a good option to the Trump campaign. It would also explain why, pushed by The Washington Post to name his foreign policy advisers on March 21, 2016, Trump blurted out: “Carter Page, PhD.” (Page received this degree in 2012 from the University of London).

The Surveillance of Carter Page

Soon after Trump named Page as an adviser, his team began to have second thoughts. In June, Page had shocked a closed door meeting of foreign policy experts when he praised Russian President Vladimir Putin as a better leader than President Barack Obama.

A month later, during a speech to Moscow’s higher education institute, the New Economic School, Page openly criticized U.S. policy. “Washington and other Western capitals have impeded potential progress through their often hypocritical focus on ideas such as democratization, inequality, corruption and regime change,” he told the audience.

In August, Trump spokeswoman Hope Hicks told The Washington Post that Page “does not speak for Mr. Trump or the campaign.” In September, the campaign’s communications director, Jason Miller, went a step further. Page, he told The Hill, has “never been a part of our campaign. Period.” That same month, Page announced he was taking a leave of absence from Trump’s campaign.

So, why the surveillance?

According to The Washington Post, which first reported that Page was under surveillance Tuesday: “The government’s application for the surveillance order targeting Page included a lengthy declaration that laid out investigators’ basis for believing that Page was an agent of the Russian government and knowingly engaged in clandestine intelligence activities on behalf of Moscow.”

Security officials’ suspicion of Page dates back to 2013. As BuzzFeed News first reported, that year, Page met with a Russian spy named Victor Podobnyy in New York City. According to a 2015 case federal prosecutors brought against Podobnyy, Page also provided him with documents. (The prosecutors did not, however, charge Page).

Given the secrecy of the FISC, little more has been revealed about why it authorized surveillance of Page. According to a so-called “dirty dossier” a former MI5 official compiled into Trump’s connections with Russia, Page allegedly met with Igor Sechin, chief executive of Rosneft and a close ally of Putin’s, in July 2016. The Washington Post suggests that this meeting, if it happened, might have interested the FBI, not least because Sechin is subject to U.S. sanctions.

This doesn’t mean that the FBI secured its warrant based on scant information. In March, FBI director James Comey told the House Intelligence Committee that the accumulated paperwork to get a warrant is often “thicker than my wrists.” Though Comey refused to discuss Page, Democrats at the hearing—one of whom cited the unverified dossier—singled him out as a figure of concern. Security experts say Page’s admiration for Putin, his personal investment in Gazprom, and his time spent in Russia are all reasons why he might have triggered alarm bells within the FBI.

The real question though is how significant Page was during the Trump campaign. His connection to Russia is undisputed—what’s unclear is whether he had any influence on Trump at all.